Characterization of Aquatic Humic Substances from Bog Water and their Complexation Behavior Toward Uranyl Ions

The investigation of the effects of humic substances (humic and fulvic acids) on the migration of radionuclides is important to assess their impact on the long-term safety of both radioactive waste repository sites (e.g. Gorleben, Germany) and abandoned uranium mines (Saxony and Thuringia, Germany).
We extracted humic substances from bog water of the 'Hochmoor Kleiner Kranichsee' which is in the vicinity of the uranium mining sites at Johanngeorgenstadt (Saxony). The humic material was separated into humic and fulvic acid fractions and characterized for its elemental composition, functional properties including proton exchange capacity, charge/size distribution ratios and spectroscopic characteristics. The size and size distribution of humic colloids were studied by photon correlation spectroscopy. Furthermore, the complexation of site specific humic substances with uranyl ions was studied. The results were compared with data of a commercial humic acid from Aldrich.